Electrical apparatus and alpha method of manufacturing it



Nov. 22, 1932. 0, LARSEN 1,888,275

ELECTRICAL APPARATUS AND A METHOD OF MANUFACTURING IT Filed July 7, 1931 Patented Nov. 22', 1932 UNITED STATES PATENT OFFICE LEONARD O. LARSEN, 0F DOWNERS GROVE, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK ELECTRICAL APPARATUS AND A METHOD OF MANUFACTURING IT Application filed July 7, 1931.

This invention relates to electrical apparatus and a method of manufacturing it and moreparticularly vto electrical coils and a method of manufacturing them.

It is an object of the present invention to provide a moisture impervious electrical coil and an economical method of manufacturing such a coil.

In accordance with one embodiment, the invention contemplates an electrical coil which may be produced by applying to a. core alternate layers of windings of wire and an insulating material composed of a fibrous material impregnated with a cellulose derivative, and by securing to the structure so built up, spool heads composed of a cellulose impregnated brous material. The insulating material being composed of a fibrous material. impregnated with a cellulose derivative may be secured to spool heads by dipping the ends of the coil in a bath of cellulose acetate dissolved in acetone and forcing the heads into engagement with the layers of interleaving material to cause the heads to coalesce to each layer and provide a moisture impervious envelope for each layer of winding. After the spool has been so formed, a protective covering composed of a librous material comprising a fabric impregnated with a cellulose derivative and faced with sheets of cellulose material coalesced to theimpregnated sheet is wrapped with overlapping edges about the wound coil, and the overlapping edges coalesced by applying an acetone solution to the fabric.

Other objects and advantages ofthe invention will more fully appear from the following detailed description, reference being had to the accompanying drawing, wherein Fig. 1 is a front elevational view of a completed coil; i

Fig. 2 is an end elevational view ofthe structure sl'own in Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view taken on the line 3-3 of Fig. 2 in the dinection of the arrows, and

Fig. 4 is an enlarged fragmentary sectional view taken on the line 4-4 of Fig. 1 in the direction of the arrows.

Referring now to the drawing whereinv Serial N0. 549,285.

like reference characters designate the same parts throughout the several views, the numeral 5 indicates generally an electrical coil constructed in accordance with this invention comprising a core member (i upon which has been applied a wrapping of paper impregnated with cellulose acetate and held in place by a serving of an insulated conductor 7 upon which in turn is superposed a layer 8 of paper impregnated with cellulose acetate. Alternate layers o'f servings of insulated electrical conductor and cellulose acetate impregnated paper are wound upon the core until the desired number of turns to provide the required electrical characteristics for the coil have been applied to the core whereupon a sheet 9 of muslin or other fabric preliminarily impregnated with cellulose acetate and then having sheets of cellulose acetate applied to each face thereof and coalesced thereto by the application of heat and pressure to the assembled fabric and cellulose material is wound about the core with its edges overlapping as shown at l0. Prior to applying the composite sheet just described, the abutting edges thereof are treated with a solution of acetone which may be either sprayed on the sheet or applied thereto with a brush whereupon they are pressed together manually and permitted to coalesce to provide a sealed protective covering.

After the coil form has been so wound, the ends of the coil are dipped in a solution of cellulose acetate in acetone and preformed heads 11 and l2 composed of a cellulose material, such as layers of paper or fabric impregnated with cellulose acetate, are forced into intimate engagement with the edges of the coil and permitted to be coalesced to each layer ofl interleaving cellulose acetate impregnated paper as shown at 14 (Fig. 3), to seal the layers of windings of insulated conductor in separate individual envelopes comprised of the heads 11 and 12 of the coil and the layers 8 of interleaving paper. Suitable leads having been taken from the ends of the coiled conductor., passed through the head l1 of the spool in any known manner and fixed to terminals 15 nd 16 to permit the coil to be connected in an electrical cir cuit.

In a completed coil as shown in Figs. l and 4, the protective covering is coalesced along the overlapping portions and the separate layers of cellulose acetate impregnated paper used for interleaving between the lay ers of winding 7, are coalesced to the heads andin eiiect provide a separate envelope for each layer of windings of conductors 8 which envelopes are 'impervious to moisture and insnlatively separate the winding. With this type of construction, there is no necessity for further securing the heads to the coil and the protective covering of cellulose acetate impregnated and sheathed inuslin provides a water impervious covering having a high degree of mechanical strength.

The term cellulose material is used in the.

appended claims to refer to material com posed of a pure cellulose derivative or paper or other fibrous sheets impregnated with a cellulose derivative and/ or muslin, paper or other fibrous material impregnated with a cellulose derivative or paper or fabric impregnated'with cellulose derivative and having sheets of cellulose acetate or other suitable esters of cellulose coalesced' to each other through the sheet of fibrous material, and the term solvent as employed in the appended claims, is intended to include not only true solvents of the .cellulose material, but also to include plasticizers.

Although the invention has been described as applying to an article having layers of paper between the servings of insulated conductor and a muslin and cellulose derivative composite sheet as a protective covering, it will be understood that various modifications of the described article and process may. be

' made without departing from the scope of the invention which is to be limited only by vthe scope ofthe appended claims.

What is claimed is: l. A method of forming electrical coils comprising assembling alternate layers of insulating material and the conducting material on a core, dissolving the edges of the insulating material, and coalescing a head comprising a similar insulating material to the layers ofinsulating material.

2. A method of forming electrical coils comprising interposing servings of conductors between layers of insulating material, dissolving the edges of the layers of insulating material, and coalescing a sheet of similar material to the layers of insulating material.

3. A method of forming electrical coils which comprises interposing servings of conductors between layers of a cellulose material, dissolving the edges of the layers of cellulose material, and coalescing a sheet of cellulose material to the dissolved edges.

4. A method of forming electrical coils comprising 'interposing servings of conducv ing sheets of paper impregnated with a cel- Lessors pregnated with a cellulose derivative, dissolving the edges ofthe cellulose impregnated fibrous material, and coalescing a sheet of cell lulose impregnated fibrous material to the -J dissolved edges.

5. A method of forming electrical coils comprising interposing servings of conductors between layers of paper impregnated with a cellulose derivative, dissolving the edges of the cellulose impregnated paper, and coalescing a sheet of paper impregnated with a cellulose derivative to the dissolved edges.

6. A method of forming electrical coils comprising interposing servings of c0nduc tors between layers of paper impregnated with a cellulose derivative, treating the edges oi' the cellulose impregna-ted paper with a solvent of the cellulose derivative, and coalesclulose derivative to the dissolved edges.

7. A method of forming electrical coils vcomprising interposing servings of conductors between layers of cellulose acetate impregated paper, treating the edges of the cellulose acetate impregnated paper with a solvent, and coalescing a sheet of cellulose acetate impregnated paperto the dissolved edges.

8. A method of forming an electrical coil comprising applying to a core alternate layers of cellulose. material and servings of conductors, treating .the ends of the layersof cellulose material with a solution including a cellulose derivative to dissolve partially the edges of the layers of cellulose material, and applying a head composed of a cellulose derivative to the edges of the layers of cellulose material to coalesce the head to the coil.

9. A., method of producing an electricalv coil coniprisingl winding alternate layers of conductors and a cellulose material, partially dissolving the edges of the cellulose material,l and securing a head of cellulose material to the layers of cellulose material by coalescence.

10. A.method of producing an electrical coil comprising winding alternate layers of conductors and a cellulose material, partially dissolving the edges of the cellulose material, applying a head of cellulose material to the layers of cellulose material to cause the layers and headto coalesce, and applying a protective covering tothe wound material comprising a sheet of fibrous material impregnatedlf with a cellulose derivative with overlapping edges and coalescing the overlapping4 edges.

11. A method of forming an electrical coil which comprises applyin to a core alternate layers of conductors an insulators, applying to the outer insulator a sheet composed of a fibrous material impregnated with a cellulose derivative with the edges'of. the ma.- terial overlapping, and coalescin'g the overlapping edges.

12. A method of forming an electrical coil which comprises applying to a core alternate layers of conductors and paper im regnated with a cellulose derivative, dissolving the edges of the cellulose impregnated paper, coalescing a sheet of paper impregnato with a cellulose derivative to the dissolved edges, applying to the outer layer of paper a sheet composed of a fibrous material impregnated with a cellulose derivative with the e ges of the material overlapping, and coalescing the overlapping edges.

13. As an article of manufacture, an electrical coil comprising alternate layers of cellulose material and conducting material, and a head composed of cellulose material coalesced to the edges of the layers of cellulose material.

14. An electrical coil com rising alternate layers of cellulose and con ucting material, a head of cellulose materialcoalesced to the edges of the layers of cellulose material, and

a protective coating comprised of cellulose material wrapped about the layers with overlappin coalesced edges.

15. is an article of manufacture, an elec-- trical coil comprising alternate layers of cellulose acetate impregnated paper' and conducting material, and a head composed of cellulose acetate impregnated paper coalesced to thev edges of the layers of cellulose acetate impregnated paper.

16. An electrical coil comprising alternate layers of cellulose acetate impre nated paper and conducting material, a hea of cellulose acetateimpregnated paper coalesced to the edges of the layers of cellulose acetate impregnated paper, and a protective coating comprised of insulating material wrappe about the layers with overlapping coalesced ed es.

n witness whereof, I hereunto subscribe my name this '25th day of June A. D., 1931. LEONARD O. LARSEN. 

